This invention relates to a control apparatus for stabilizing combustion in an engine.
A device for controlling gas flow in a combustion chamber to improve the combustion characteristic of an engine by providing two independent intake ports, a primary port and a secondary port, in a cylinder, disposing a control valve upstream of the secondary port, and opening and closing the control valve in accordance with the operating conditions, is proposed in Japanese Patent Kokai Publication JP5-163950A.
In this case, during engine low load condition the control valve is closed and air-fuel mixture is supplied only from the primary port such that a swirl is generated inside the combustion chamber and the combustion characteristic is improved. However, improvement of the combustion characteristic is limited by the swirl alone. Moreover, improvements in early catalytic activation when the engine was cold proved difficult.
An object of this invention is to provide an engine control apparatus which is designed to be capable of enhancing early catalytic activation and ensuring stable combustion even with a lean air-fuel mixture by stratifying the air-fuel mixture layer in the combustion chamber when the engine is cold condition.
In order to achieve above the object, this invention provides a control apparatus for an internal combustion engine having an intake valve and an exhaust valve, comprising at least two independent intake ports connected to an engine combustion chamber; a first fuel injection valve provided in the first intake port; and a second intake control valve for opening and closing the second intake port on the upstream side of the intake valve, wherein, when the engine is cold condition, the second intake control valve is slightly opened, fuel is injected from the first fuel injection valve, air-fuel mixture from the first intake port and a smaller amount of fresh air from the second intake port are led into the combustion chamber, and thus the overall air-fuel ratio becomes slightly lean.
The details as well as other features and advantages of the invention are set forth in the remainder of the specification and are shown in the accompanying drawings.